Summary: Anthrax is one of the biological weapons most likely to be used in terrorism or warfare. Anthrax spore laced letters caused five deaths in the fall of 2001 in America. Before a new vaccine for anthrax is developed and approved, the most important task is to assure that the current vaccineiAnthrax Vaccine Adsorbed (AVA) is safe and effective. The Laboratory of Analytical Chemistry of OVRR/CBER/FDA is currently involved in efforts to verify that this product meets the specifications. However, some of the currently used procedures for the vaccine analyses have become obsolescent due to the fact that they are based on relatively non-specific and time-consuming colorimetric techniques. In order to monitor the chemical component contents of the vaccine more accurately and precisely, new methods need to be developed with the help of modern instrumentation such as HPLC/MS. The goal of this project is to develop a new HPLC method for the determination of formaldehyde and to explore the possibility of detection and determination of the protective antigen in AVA by HPLC/MS. The results of this research are expected to provide better analytical methods for both the quality control by the manufacturer and regulatory monitoring by the FDA.